Collagen is commonly used in the preparation of food casings but the manufacture of such products, in particular, meat products, is frequently complicated by the frailty of the product. This is aggravated by the necessity that such products be stuffed at low temperatures, generally at temperatures lower than 40.degree. F. At these low temperatures, there is an increased probability of mechanical breakage of the casings. This is commercially undesirable since significant blocks of time would be lost due to downtime for cleaning and restarting.
Over a period of years, thick walled synthetic sausage casings have been prepared from animal collagen. Collagen casings have been prepared by processing the corium layer of animal hides to break the collagen into a fibrous structure. The collagen fibers are then extruded in the form of a doughy mass to produce tubular casings. The casings which have been prepared in this manner have been hardened by treatment with aluminum salts followed by formaldehyde and/or other aldehydes and have been used as removable casings for processing various sausages. These casings have not been edible even though collagen itself is edible. Even if it were edible, products made with these casings would not be commercially desirable.
The thickness of the casing for edible products would have many disadvantages. On the consumer level, there would be a lack of appeal because of the dense appearance and the difficulty in chewing a product made with such a thick casing. On the commercial level, there would be a waste of materials and increased cost in producing these thick walled casings. The thick walls make modern high speed stuffing more difficult. In addition, they require greater packaging room, e.g. in shirred casings.
Thinner walled edible sausage casings of collagen have been prepared and sold in commercial quantities. In the manufacture of these casings, one approach uses a collagen source material which has not been subjected to a liming treatment. Another technique makes use of limed collagen source material by observing special processing methods. Although both methods are capable of producing casings which are edible and have other advantageous properties adapting them for use as sausage casings, these methods do not overcome the disadvantage of requiring relatively extensive and involved processing and handling procedures due to its frailty.
It is therefore an object of the invention to provide a strengthened casing product which comprises collagen and which is useful as sausage casings wherein the disadvantages of the prior art collagen materials are overcome.
It is a further object of the present invention to provide collagen casings which are of sufficiently high mechanical strength to resist breakage during sausage manufacturing processes at low temperatures.
It is a further object of the present invention to provide collagen casings which are of sufficiently high mechanical strength that the thickness of the casings can be considerably reduced when compared with prior art casings.
It is a further object of the present invention to provide a method for preparing collagen type casings of high mechanical strength by which the disadvantages of the prior art processes are avoided.
Another object of the invention is to provide such a casing having good antimycotic properties.
Still another object of the invention is to accomplish the foregoing objects while providing an edible collagen casing.
Additional objects, if not specifically set forth herein, will be apparent to one skilled in the art from the following description of the invention.